To the Editor: Dr Pryor and colleagues1 reported that hyperoxia increased the risk of surgical
wound infection. In contrast, Greif et al2 reported
that hyperoxia decreased the risk. One possible explanation for these discrepant
results may relate to the rate of oxygen delivery to the wound itself. In
healthy awake volunteers, as well as in anesthetized patients, cardiac output
is reduced and systemic vascular resistance increased following the exposure
to normobaric hyperoxia.3,4 Oxygen
delivery is the product of cardiac index and arterial oxygen content. Increasing
the fractional inspired oxygen (FIO2) from 30% to 80% causes a
small (0.5%) increase in arterial oxygen saturation, and consequently higher
arterial oxygen content; however this was more than counteracted by a decrease
(6%) in cardiac index.3